diff --git a/index.php b/index.php
index 4d125f332..9379b7637 100644
--- a/index.php
+++ b/index.php
@@ -2,13 +2,13 @@
 namespace Grav;
 
 if (version_compare($ver = PHP_VERSION, $req = '5.4.0', '<')) {
-    exit(sprintf('You are running PHP %s, but Grav needs at least <strong>PHP %s</strong> to run.', $ver, $req));
+    throw new \RuntimeException(sprintf('You are running PHP %s, but Grav needs at least <strong>PHP %s</strong> to run.', $ver, $req));
 }
 
 // Ensure vendor libraries exist
 $autoload = __DIR__ . '/vendor/autoload.php';
 if (!is_file($autoload)) {
-    exit('Please run: <i>bin/grav install</i>');
+    throw new \RuntimeException("Please run: <i>bin/grav install</i>");
 }
 
 use Grav\Common\Grav;
diff --git a/system/src/Grav/Common/Assets.php b/system/src/Grav/Common/Assets.php
index 4e940d09e..4027b07d2 100644
--- a/system/src/Grav/Common/Assets.php
+++ b/system/src/Grav/Common/Assets.php
@@ -120,7 +120,7 @@ class Assets
         }
 
         // Set custom pipeline fetch command
-        if (isset($config['fetch_command']) and ($config['fetch_command'] instanceof Closure)) {
+        if (isset($config['fetch_command']) && ($config['fetch_command'] instanceof Closure)) {
             $this->fetch_command = $config['fetch_command'];
         }
 
@@ -143,12 +143,12 @@ class Assets
         }
 
         // Set collections
-        if (isset($config['collections']) and is_array($config['collections'])) {
+        if (isset($config['collections']) && is_array($config['collections'])) {
             $this->collections = $config['collections'];
         }
 
         // Autoload assets
-        if (isset($config['autoload']) and is_array($config['autoload'])) {
+        if (isset($config['autoload']) && is_array($config['autoload'])) {
             foreach ($config['autoload'] as $asset) {
                 $this->add($asset);
             }
@@ -651,9 +651,9 @@ class Assets
             $info = pathinfo($asset);
             if (isset($info['extension'])) {
                 $ext = strtolower($info['extension']);
-                if ($ext === 'css' and !in_array($asset, $this->css)) {
+                if ($ext === 'css' && !in_array($asset, $this->css)) {
                     $this->css[] = $asset;
-                } elseif ($ext === 'js' and !in_array($asset, $this->js)) {
+                } elseif ($ext === 'js' && !in_array($asset, $this->js)) {
                     $this->js[] = $asset;
                 }
             }
@@ -673,8 +673,8 @@ class Assets
      */
     protected function isRemoteLink($link)
     {
-        return ('http://' === substr($link, 0, 7) or 'https://' === substr($link, 0, 8)
-            or '//' === substr($link, 0, 2));
+        return ('http://' === substr($link, 0, 7) || 'https://' === substr($link, 0, 8)
+            || '//' === substr($link, 0, 2));
     }
 
     /**
diff --git a/system/src/Grav/Common/Errors/Errors.php b/system/src/Grav/Common/Errors/Errors.php
index 57dfbd85a..bd03455b0 100644
--- a/system/src/Grav/Common/Errors/Errors.php
+++ b/system/src/Grav/Common/Errors/Errors.php
@@ -23,7 +23,7 @@ class Errors extends \Whoops\Run
         }
 
         if (!$handler instanceof HandlerInterface) {
-            throw new InvalidArgumentException(
+            throw new \InvalidArgumentException(
                 "Argument to " . __METHOD__ . " must be a callable, or instance of"
                 . "Whoops\\Handler\\HandlerInterface"
             );
diff --git a/system/src/Grav/Common/Errors/SimplePageHandler.php b/system/src/Grav/Common/Errors/SimplePageHandler.php
index f0c6749fb..8584900fa 100644
--- a/system/src/Grav/Common/Errors/SimplePageHandler.php
+++ b/system/src/Grav/Common/Errors/SimplePageHandler.php
@@ -46,6 +46,11 @@ class SimplePageHandler extends Handler
         return Handler::QUIT;
     }
 
+    /**
+     * @param $resource
+     *
+     * @return string
+     */
     protected function getResource($resource)
     {
         // If the resource was found before, we can speed things up
@@ -67,7 +72,7 @@ class SimplePageHandler extends Handler
         }
 
         // If we got this far, nothing was found.
-        throw new RuntimeException(
+        throw new \RuntimeException(
             "Could not find resource '$resource' in any resource paths."
             . "(searched: " . join(", ", $this->searchPaths). ")"
         );
@@ -76,7 +81,7 @@ class SimplePageHandler extends Handler
     public function addResourcePath($path)
     {
         if (!is_dir($path)) {
-            throw new InvalidArgumentException(
+            throw new \InvalidArgumentException(
                 "'$path' is not a valid directory"
             );
         }
diff --git a/system/src/Grav/Common/Markdown/ParsedownGravTrait.php b/system/src/Grav/Common/Markdown/ParsedownGravTrait.php
index b85a98064..4cdbe0c6b 100644
--- a/system/src/Grav/Common/Markdown/ParsedownGravTrait.php
+++ b/system/src/Grav/Common/Markdown/ParsedownGravTrait.php
@@ -72,7 +72,7 @@ trait ParsedownGravTrait
 
     protected function inlineSpecialCharacter($Excerpt)
     {
-        if ($Excerpt['text'][0] === '&' and ! preg_match('/^&#?\w+;/', $Excerpt['text'])) {
+        if ($Excerpt['text'][0] === '&' && ! preg_match('/^&#?\w+;/', $Excerpt['text'])) {
             return array(
                 'markup' => '&amp;',
                 'extent' => 1,